Motion picture film drive



Aug. 15, 1939. E. MAY

MOTION PICTURE FILM DRIVE Filegl Jan 21, 1938 INVENTOR 7 m); fl/gy BY owim Patented Aug. 15, 1939 v UNITED STATES PATENT OFFICE MOTION PICTURE FILM DRIVE Erwin May, Wetzlar, Germany, assignor to Ernst Leitz, G. in. b. H., Wetzlar, Germany Application January 21, 1938, Serial No. 186,026

5 Claims. (01. 74-436) This invention relates to improvements in driv- S-formed cam 8 adapted to engage in the wider ing means for the film transport roller in a moslits l3 in the star wheel to rotate the latter and tion picture projection machine and for like purthe roller l sufiiciently to shift the film one picposes. ture length as will be understood. The two It has been proposed to providethe shaft of shafts I and 2 have intermeshing gears 3 and 4 -5 the film transport roller with a star wheel which for driving these shafts at the same speed. Either is driven from a shaft provided with a cam for of the gears 3 and 4 may in turn be driven from rotating the star wheel and another cam for keepthe projection machine mechanism in any suiting the star wheel immovable while the film is able manner not shown.

projected. The spaces between the teeth. in the It is clear from Fig. 1 that so long as the 10 star wheel are necessarily short so that when the rotating guides i, i engage the star wheel, the one cam passes through said spaces to rotate the latter and the film transport roller stands still wheel it exerts great pressure upon the teeth so that the film can be projected. As soon as the which quickly Wears them down. This in turn guides i become disengaged from the star wheel,

causes play between the two elements which rethe latter is engaged by the cam 8 which causes sults in uneven film projection. sufiicient rotation of the star wheel and the film The object of this invention is to provide an transport roller to shift, the film. improved driving mechanism for the film trans- The modification in Fig. 2 consists in providing port roller whereby to reduce friction, wear and the second shaft 22 with a single guide l8 which M tear and obtain more even projection. is adapted to engage the wider slits l3 of the star To this end the invention is embodied in a drivwheel. The second shaft 22 is slidably supported ing mechanism in which cams and guides for in the framework [4 and I5 and is held against an operating the star wheels are separated and actuating cam I1 upon a shaft 25 which is driven mounted upon two shafts. The spaces between in any suitable manner not shown. A spring l6 s the teeth on the star wheel are alternately large presses against the guide I8 and thus keeps the 25 and small. The larger spaces are for the enshaft 22 in operative engagement with the actugagement of the cam which rotates the star wheel ating cam I1. and the film transport roller. The smaller or So long as the guides 1 engage the narrower narrower spaces are engaged by rotating guides slits 12 in the star wheel, the latter and the I0 which holds the star wheel and film transport film transport roller ill stand still and the film is roller immovable while the picture is projected. projected. The timing is such that as the guides In the accompanying drawing illustrating the I leave the star wheel, the guide l8 engages a slit invention IS in the star wheel and as said guide l8 rotates,

Fig. 1 is a View of a film transport roller drivthe shaft 22 and the guide 18 are shifted trans- :5 ing mechanism embodying the invention, with versely to the roller shaft ID by the actuating parts in section and parts removed, cam I! as will be understood. Hence the guide Fig. 2 is a similar view showing a modification. 18 causes the star wheel and the film transport Fig. 3 is a detail View showing the relations of roller to rotate sufiiciently to shift the film one the cams and guides to the star wheel. picture length between projection periods. When In Fig. 1 the reference numeral l0 indicates the guide [8 leaves the star wheel it is moved 40 the film transport roller for driving the film 2|]. back into initial position by the cooperation of The roller is fast on a shaft 9 which carries a the cam IT and the spring [6. gear or star wheel II having teeth which are The mechanism herein disclosed has been found separated by spaces l2 and Hi. The spaces or advantageous in that it includes the possibility of slits l2 are narrower than the spaces or slits l3 better dimensioning of the teeth on the star 45 and said differently dimensioned slits alternate -.wheel to reduce friction and wear and tear. It as shown. The frame of the projection machine also includes the advantages of employing star is generally indicated at M and I5. wheel actuating cams of relatively smaller radii Above the shaft 9 there is suitably mounted a, whereby to flatten the Curve of e fil 0n the shaft I having a drum 5 provided with two guides roller 0. 50

I, l the planes of which are perpendicular to the e ve e includes Within its Scope the a axis of the shaft I. The guides I are spaced so as ternative construction of using two star wheels to simultaneously engage two narrow slits l2 in one for each of the guides and cam I and 8 and the star wheel as shown. Below the latter there guide i8 resp v ly Such alternative o strucis another shaft 2 with a drum 6 provided with an tion being rather obvious is not shown. 66

I claim:

1. In a motion picture machine, a film transport roller for operating the film, said roller having a period of rest while the film is projected and a period of rotation to shift the film between projection periods, a gear wheel in fixed relation to said roller, means to engage and hold the gear wheel and film transport roller immovable during projection periods, means for moving the holding means out'of engagement with the gear wheel, longitudinally shiftable means for engaging the gear wheel to advance the film between projection periods when the holding means is out of engagement with said gear wheel, and means for actuating the shiftable means.

2. In a motion picture machine, a film engaging member for advancing theffilm, a gear connected to said member, shiftable means for intermittently engaging said gear to advance the film between projection periods, means for moving said shiftable means into engagement with said gear, means for moving said shiftable means out of engagement fWlth said gear, means for holding said gear and thereby the film against movementin either direction when the shiftable 'means is-out of engagement therewith, and

means'for' actuating all of said parts.

3. In a motion picture machine, a film engaging member for advancing the film, a. gear connected to said member, means for intermittently engaging and rotating said gear whereby to ad Vance the film between projection periods, said means being normally biased in one direction, means for moving said last named means into operative engagement with said gear, holding means for the gear and film to prevent movement thereof in either direction during projecactuating the shiftable means,

tion periods of the film, and means for actuating the holding means to cause intermittent engagement and disengagement with the gear at predetermined intervals.

4. In a motion picture machine, a film engaging member for advancing the film, a gear connected to said member, slidable means for intermittently engaging and rotating said gear whereby to advance the film between projection periods, a cam for engaging and actuating the slidable means, means for normally biasing the slidable means toward the cam, means for holding the gear to prevent movement of the film in either direction during the projection periods thereof, and means for continuously moving the holding means into and out of operative engagement with the gear at predetermined intervals.

5. In a motion picture machine, a film transport roller for operating the film, said roller having a period of rest while the film is projected and aperiodof rotation to shift .thefilmbetween projectionperiods, a .gear wheel in fixed relation to said roller, ,a continuously rotating member to engage and hold the gear wheel and film trans- .port .roller. immovable during projection periods,

a shaftwfor rotating said member to move the same into and outlof engagement with the gear wheel, shiftable means for engaging the gear wheel to advance the film between projection periods when the said holding member is out of engagement with said gear wheel, a shaft for intermeshing gears on the said two shafts, and means on the second named shaft for moving the shiftable means axially independently of the first named 3 shaft.

. ERWIN MAY. 

